Two-stroke internal-combustion engine



J. ROMEYN TWO-STBOKE INTERNAL COMBUSTION ENGINE Filed July s, 1923 Pia-.1 1

Patented Jan. 6, 1925 JEAN ROMEYN, OF BRUSSELS, BELGIUM.

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TWO-STROKE INTERNAL-COMBUSTION ENGINE.

Application filed July 3,

To all whom it may concern:

Be it known that I, JEAN ROMEYN, a citizen of the Kingdom of Netherlands, and resident of Brussels, Belgium, have invented certain new and useful Improvements in or Relating to Two-Stroke Internal-Oombustion Engines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to the accompanying drawlngs, and to letters or figures of reference marked therein, which form the part of this specification. i In a two-stroke internal combustion engine, as is well known, the maximum output which can be obtained from a given. cylinder depends upon the back pressure in the exhaust pipe.

Two different cases of an increase in the back pressure will now be discussed, supposing all the other conditions to be unaltered.

Firstly, if the engine is so designed that the scavenging valves or parts close after the exhaust ports have closed again the back pressure increase results in the pressure in the cylinder during the scavenging period becoming higher, and the same applies to the scavenging air pressure. Consequently, as the cylinder is filled at a pressure substantially equal to thescavenging air pressure, the pressure at the beginning of the compression is higher, and more fresh air is compressed bythe piston.

Secondly, if the scavenging is effected through ports only, and without any additional distributing arrangement, these ports, which necessarily open after the exhaust ports, are closed first and the pressure at the beginning of the compression is substantially equal to the back pressure in the exhaust pipe. In this case it is obvious that any increase of this back pressure is fav0urable as regards the quantity of fresh air enclosed in the cylinder.

It would be very easy to obtain any given back pressure in the exhaust pipe by arrang ing at the end thereof a restricted passage if the lead and the speed of the engine were constant. But, as the volume of burnt gas exhausted by the engine in a time unit is 1923. Serial No. 649,349.

variable owing to the exhaust temperature, and as the case may be, to the speeduof the engine, the back pressure obtained by means I.

of a restricted passage of constant area would vary and consequently also the compresslon pressure. Such variations of the compression are only permissible when they engine. But such a valve is liable to be-. come clogged owing to the dirt of the exhaust gas.

The object of the present invention is to obtain a certain regulationof the back pressure withoutusing any valve or mechanism in the exhaust pipe; and to effect this, there is discharged into the exhaust pipe a variable quantity of scavenging air, in such .a manner that the flow of fresh air meeting with the flow of burnt gas creates disturbance and so increases the resistance encountered by said gas.

In order that the invention may be readily understood, it is represented by way of example in the accompanying drawings in which: Figure 1 is a diagrammatic vertical section, showing the invention in its simplest form; Fig. 2 is a similar sectional view of a form analogous to that illustrated in Fig. 1, but equipped with an obstructing element; and Fig. 3 is likewise a diagrammatic, vertical sectional view, but showing the invention applied to the exhaust si lencer.

In Figure 1 the burnt gas flows through the pipe 5 0 in the direction shown by'the arrow a, (Z is an annular space or chamber encircling pipe 0 and receiving through the pipe 6 a certainquantity of scavengin air which can be adjusted by means of the valve 7", which as the case may be is controlled by 1 hand, or by the governor or by the speed regulating gear. The chamber (Z communicates with the pipe 0 thr'oughan annular slot 9, which is so disposed that the flow of fresh air entering the pi 3e is directed backwards with respect to the direction of the burnt gas flow.

It must be considered that for a given load and speed of the engine, the total vol* ume of fluid (air and exhaust) which must pass through the mouth it of pipe 0 is constant. If the valve f is closed, the whole quantity of gas flows gently in the direction a without encountering other resistances than those caused by the pipe. But if part of the scavenging air is admitted through the slot 9, there is an additional resistance due to disturbance.

Supposing that the area of the pipe is suitable for obtaining at full load and full speed the back pressure and the compression required',-it will be possible to suppress or to minimize the difiierences of compression due to the variations of load and speed by admitting more or less fresh air through the pipere.

In Figures 2-and 8, the same letters designate similar parts as in Figure 1. The form shown in Figure 2 is similar to that shown in Figure 1, except that the part i is inserted in the pipe 0 at the place where the scavenging'air is admitted, in order to have an annular passage h of small width, which is favourable'to the disturbance.

In Figure 3 the device is appliedto the exhaust silencer J but the principle is just the same.

lVhat I claim is :c

1. An attachment for two-stroke internal combustion engines, for regulating the back pressure within the engine cylinder in accordance with the load and speed of the engine, said attachment comprising: a hollow-element to receive the exhaust gases from the engine, a discharge pipe "for said gases opening into the receiving element, and means for admitting a supply of fresh air into said element to impact against the exhaust gas current and thereby create a disturbance therein which will resist the passage of said current.

2. An attachment for twostroke internal combustion engines, for regulating the back pressure within the engine cylinder in accordance with the load and speed of the engine, said attachment comprising: a hollow element to receive the exhaust gases from the engine, a discharge pipe for said gases projecting at its inlet end into the receiving element, said element providing an internal chamber which encircles the pro jeetin'g end of said pipe and which communicates with the bore of the latter through an annular slot, and a pipe for supplying fresh air to said chamber to pass into the discharge pipe by way 01 said slot and to impact against the exhaust gas.

3. An attachment for two-stroke internal combustion engines, for regulating the back pressure within the engine cylinder in accordance with the load and speed of the engine, said attachment comprising: a helllow element to receive the exhaust gases from the engine, a discharge pipe for said gases projecting at its inlet end into the re ceiving element, said element providing an internal chamber which encircles the projecting end of said pipe and which communicates with the bore of the latter through an annular slot, and a pipe for supplying fresh airto said chamber to pass into the discharge pipe by way of the slot and to impact against the exhaust gas; said slot being so disposed that the current of incoming air flows therethrough in a direction substantially opposite that of the gas current.

4. An attachment for two-stroke internal combustion engines, for regulating the back pressure Within the engine cylinder in accordance with the load and speed of the engine, said attachment comprising: a hollow element to receive the exhaust gases from the engine, a discharge pipe for said gases projecting at its inlet end into the 'receiving element, said element providingan internal chamber which encircles the pro jecting end of said pipe and which com municates with the bore of the latter through an annular slot, and'a pipe for supplying a certain quantity of scavenging air to said chamber to pass into the discharge pipe by way of said slot and to impact against the exhaust gas.

5. An attachment tor two-stroke internal combustion engines, for regulating the back pressure within the engine cylinder in ac cordance with the load and speed of the engine, said attachment comprising; a hollow element to receive the exhaustgases from the engine, a discharge pipe for said gases projecting at its inlet end into the receiving element, said element providing an internal chamber which encircles the projecting end of said pipe and which com municates with the bore. of the latter through an annular slot, a pipe forsupplying fresh air to said chamber to pass into the discharge pipe by way of said slot and to impact against the exhaust gas, and a throttling device in the air supply pipe for controlling the flow 01? air therethrough.

6. An attachment for two-stroke.internal combustion engines, for regulating the back pressure within the engine cylinder in accordance with the load and speed of the engine, said attachment comprising: a hollow element to receive the exhaust gases from the engine, a discharge pipe for said gases projecting at its inlet end into the receiving element, said element providing an internal chamber which encircles the projecting end of said pipe and which communicates with he bore of the latter through an annular slot, a pipe for supplying fresh air to said chamber to pass into the discharge pipe by way of said .slot and to impact against the exhaust gas, and an obstructing element mounted in the inlet In testimony whereof I aflix my signature end of sald discharge pipe to provide an in the presence of two Witnesses. annular inlet space between the Walls of the latter and of the obstructing element, there- JEAN ROMEYN. 5 by to increase the disturbance initially Witnesses:

created in the receiving element by the im- LEONARD LEVIE,

pact of the air and gas. MARIE DEFREALY. 

